Hexagonal Warping Control of Exceptional Points in Topological Insulator--Ferromagnetic Heterojunctions

TL;DR

This paper explores how hexagonal warping influences the formation and control of exceptional points in topological insulator-ferromagnet interfaces, providing a tunable platform for non-Hermitian physics.

Contribution

It reveals the role of hexagonal warping in determining and tuning exceptional points in topological insulator-ferromagnet heterojunctions, advancing understanding of non-Hermitian phenomena.

Findings

Hexagonal warping affects the location of exceptional points.

Magnetic fields can tune the number and position of EPs.

The platform is experimentally accessible for non-Hermitian physics studies.

Abstract

Exceptional points (EPs) are non-Hermitian degeneracies, where both eigenvalues and eigenvectors coalesce, which are fundamentally distinct from their Hermitian counterparts. In this study, we investigate the influence of hexagonal warping on EPs emerging at the interfaces between topological insulators and ferromagnets. We demonstrate that the presence of the warping term plays a crucial role in determining the locations of the EPs. Furthermore, we show that the number as well as the positions of EPs emerging at such junctions can be tuned by an applied magnetic field. Our results establish a realistic and experimentally accessible platform for exploring non-Hermitian physics in topological insulator-ferromagnet junctions.